Largest Possible PRK Optical Zone - U.S. or Abroad 
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 Largest Possible PRK Optical Zone - U.S. or Abroad

I suffer from severe GASH from RK surgery performed in 1992. I have
yet to have a pupilometer test but have studied the size of my
nighttime pupils for a long time. I have used Rev-Eyes and Alphagan
with some success, but only short term.
What I am asking here is that can someone have a nighttime pupil
larger then 9MM. I have a pupil size card, which I put under a
template I have of pupil sizes. From a previous Orbscan I know that my
iris is 11.9MM. So what I do is put the pupil size card pupil (9MM)
under the template (open circle of 11.9MM). By doing this I can get an
idea of how much space is between the outside edge of the iris and the
outside edge of the pupil - on the cards. Then I compare this with my
nighttime pupil.

I believe that my nighttime pupil is at least as big as 9MM. I think
it could be close to 10MM.

I have never heard or read anything to verify that a naturally
dilating pupil can be larger than 9MM. All the studies include ranges,
which end at 9MM.

I also would like to know what is the largest pupil size possible when
an eye is artificially dilated with dilating drops at the doctor's
office. I believe that ones pupil can almost fill up the space over
the iris when artificially dilated. If this is true than why isn't it
possible to have a naturally occurring nighttime pupil of over 9MM? I
would think some people could be on some sort of medication, which can
cause the pupil to dilate - which could put their nighttime pupil over
9MM. This being true would just add to the list of pre-op screening
these hacks should be doing before going ahead with surgery. Has
anyone here been asked if and what medications they were using, before
they had refractive surgery? Or has anyone been told that if later on
in life they may need a medication, which could dilate their pupil,
that this could cause their pupil to expand past the ablation zone,
which was ablated, on the cornea? No probably is the answer. However,
I am sure you've been told after surgery that you pupil will get
smaller as you get older!

I should say here for the record that I take no medication whatsoever
and I am certain my nighttime pupil is close to 10MM.

Thus, I conclude that for me to have success in repairing my corneal
curvature I must have my entire pupil ablated. By the way, I wear
RGP's, with limited comfort success, which measure 12.5MM total
diameter with an optical zone of 10.8MM. It took me five years to find
an OD who even told me that it was possible to make an RGP this large.
Now, back to my question. If I have an iris, which is 11.9MM, and lets
say a nighttime pupil of 10MM, then what size should my ablation zone
be? I have heard many MD's (CorneaDoc is one of them) say that they
ablate 1.5MM above the nighttime pupil diameter. This would be an
ablation zone of 11.5MM for me, if my estimates are correct - which
gets me very close to my iris diameter of 11.9MM.

Does anyone know how far it is out to the limbus? I know of laser
companies who claim that they have lasers, which are capable of
ablating out to the limbus. Does the limbus go out past the iris - in
my case the iris being 11.9MM?

I know that from my experience with trying to get fit with RGP's that
I must have an RGP which has close to a 1MM larger diameter than my
estimated 10mm nighttime pupil or else the lens edge creates a flaring
effect. This is why I wear 10.8MM optical zone RGP's with a total
diameter of 12.5MM.

It should be noted that since I had RK I have plenty of tissue left
(thick corneas). However, I realize that they still have no consensus
on ablation profiles. Wavefront should solve this problem, I hope.
Does anyone know if an ablation of the entire cornea - all the way to
the limbus - would be possible on a person like me who is OD: -.25
+1.00*115; OS: -.25 +1.25*180 with moderate to severe irregular
astigmatism. Glasses don't do a thing but RGP's solve 99% of the
problems. It is very hard to tolerate these lenses for any length of

I think that, even though my prescription isn't too strong, to create
a perfectly shaped prolate cornea (an optical zone of the entire
diameter of my cornea) based on my wavefront, I would probably have to
ablate much of my peripheral cornea. What about the risk of haze for a
case like this - even with Mitomycin C?

It's time that we start getting some straight answers from the MD's
who are causing all the problems. It is becoming increasingly more
obvious that we have been deceived since refractive surgery started.
Is some MD out their brave enough to explain to us why the whole
cornea should not be the entire optical zone on people who have huge
nighttime pupils? What about those who have average pupils and are
receiving blended zones? Shouldn't these people have ONE optical zone,
1.5MM larger than their nighttime pupil? If the lasers are available
to ablate to the limbus then why aren't you telling your patients to
wait until the nomograms are worked out; if they have enough corneal
tissue then why are you doing straight 6.5MM zones or even blended

Thank You


San Francisco

Mon, 10 May 2004 12:12:22 GMT
 [ 1 post ] 

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